Saturn Moon Is Ready For Its Close-up

October 28, 2004|By Michael Cabbage, Sentinel Space Editor

CAPE CANAVERAL -- Saturn's hazy moon Titan remains as mysterious as ever after its first close encounter with the Cassini spacecraft.

Scientists at NASA's Jet Propulsion Laboratory in Pasadena, Calif., spent Wednesday examining a baffling array of images radioed back to Earth after the $3.3 billion probe flew within 750 miles of the giant moon. The pictures showed an alien world with few clouds, areas of unexplained light and dark streaks, and no evidence of liquid oceans or lakes.

"We are still mystified and we are not quite sure what we're looking at," said Carolyn Porco, leader of Cassini's imaging team. "There isn't much that we are absolutely, definitively confident about right now."

The light and dark surface regions are among the biggest puzzles. Instruments aboard Cassini seem to indicate the areas have a similar chemical makeup despite their different appearances.

Pictures taken by the spacecraft show Titan is mostly smooth with few impact craters, perhaps meaning a geologically young surface. Researchers speculated that the streaks could be the result of wind or tectonic activity like the process that constantly renews the Earth's crust.

"What we can confidently say about the structures we are seeing on the surface is that they are linear. They are streaks or perhaps they are cracks in the bedrock ice," Porco said. "We see this in lots of regions where we look with high-resolution [cameras], and we're not quite sure what it is telling us."

The moon's atmosphere proved just as interesting as its surface.

Titan rotates somewhat slowly, while the atmosphere that envelopes the moon moves much more quickly; wind speeds are comparable to those on Earth. And a layer of clouds -- consisting of thicker particles than the hydrocarbon haze that shrouds most of Titan -- covers the south-pole area.

"There is something else going on in that region that is very different from the processes that are forming the haze," said Robert Brown, Cassini's team leader for instruments used to map surface composition.

Scientists stressed Wednesday that analysis of the flyby data was still in its early stages.

Forty-four more Titan flybys, some closer than 600 miles, are planned during Cassini's four-year mission to study Saturn and its moons. The spacecraft is scheduled to deploy a small probe Dec. 24 that will plunge through Titan's atmosphere and land Jan. 14, collecting information and taking pictures during the descent.

Studying Titan could help researchers better understand Earth's origins. Bigger than the planet Mercury, Titan is the second-largest moon in the solar system and the only one with a significant atmosphere. Like Earth's atmosphere, Titan's is primarily nitrogen, and carbon-based compounds also are present there.

Launched in 1997, Cassini is jointly funded by NASA, the European Space Agency and the Italian Space Agency.